A high power density hydrogen fuel cell bipolar plate flow field

Abstract

The present invention relates to a high-power-density hydrogen fuel cell bipolar plate flow field, comprising at least one flow field plate, the flow field plate comprising cathode and anode surfaces, respectively for transporting an oxidant and a fuel. Anode flow channels are provided on the anode surface, and cathode flow channels are provided on the cathode surface. The anode and cathode flow channels form multiple flow field grooves within the anode and cathode surfaces, respectively, and each form multiple flow field ridges on the anode and cathode surfaces, respectively. The anode and cathode flow channels are interconnected by multiple flow field grooves, and adjacent flow field grooves are interconnected by multiple capillary flow channels, each disposed within a flow field ridge between adjacent flow field grooves and angled relative to the direction of material flow. The present invention reduces plate weight, enhances the mass transfer and drainage capabilities of the flow field, and thereby increases the power density of the membrane electrode by 20-30%.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a bipolar plate flow field of a high power density hydrogen fuel cell. Background Art

[0002] In recent years, the depletion of fossil resources and rising demands for environmental quality have led to an increasingly urgent need to develop clean, recyclable energy systems. Proton exchange membrane fuel cells (PEMFCs) are devices that convert chemical energy stored in hydrogen and oxygen directly into electricity, with the sole exhaust being water. This meets current demands for renewable energy and offers advantages such as high energy conversion efficiency, high power density, and an operating mode similar to that of an internal combustion engine, making them a research hotspot.

[0003] The traditional flow field groove ridge part has difficulty in material transmission and drainage, which is easy to cause local flooding and mass transfer polarization. For example, the pressure drop of the serpentine flow field is relatively high, and flooding is easy to form near the outlet. Figure 7 As shown in the figure, the parallel groove flow field pressure drop is not conducive to the discharge of liquid water inside the battery, and it is also easy to form a dead zone. Figure 5 and Figure 6 Therefore, it is urgent to design a flow field that can enhance mass transfer and drainage capacity to increase the diffusion contact area between the material and the membrane electrode, thereby increasing the battery operating current density. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high power density hydrogen fuel cell bipolar plate flow field, which effectively enhances mass transfer and strengthens drainage capacity.

[0005] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0006] A high power density hydrogen fuel cell bipolar plate flow field includes at least one flow field plate, wherein the flow field plate includes a cathode and an anode surface, which are respectively used for the transmission of oxidant and fuel, an anode flow field channel is provided on the anode surface, and a cathode flow field channel is provided on the cathode surface, the anode flow field channel and the cathode flow field channel respectively form a plurality of flow field grooves in the anode surface and the cathode surface, the anode flow field channel and the cathode flow field channel respectively form a plurality of flow field ridges on the anode surface and the cathode surface, the anode flow field channel and the cathode flow field channel are both connected by a plurality of flow field grooves, and a plurality of capillary flow channels are connected between two adjacent flow field grooves, and the capillary flow channels are arranged in the flow field ridge between the two adjacent flow field grooves and are arranged at an angle to the material flow direction.

[0007] Preferably, the capillary flow channel and the material flow direction form an angle Q, 10°<Q<90°.

[0008] Preferably, the pressures of two adjacent flow field grooves connected by the capillary flow channel are P1 and P2 respectively, and ΔP=P1-P2≠0.

[0009] Preferably, the cross-sectional shape of the capillary flow channel is any one of semicircular, inverted triangle, rectangular or sawtooth.

[0010] Preferably, the width of the capillary channel is D, 0<D<0.5mm.

[0011] Preferably, the depth of the capillary channel is H, 0<H<0.3mm.

[0012] Preferably, the inner surface of the capillary channel is treated with a hydrophobic agent.

[0013] Preferably, the hydrophobic agent is PTFE or PVDF.

[0014] Preferably, the flow field plate is a serpentine flow field plate or a parallel flow field plate.

[0015] Preferably, an inlet is provided at one end of the cathode flow field channel or the anode flow field channel, and an outlet is provided at the other end of the cathode flow field channel or the anode flow field channel, and both the inlet and the outlet are connected to the cathode flow field channel or the anode flow field channel.

[0016] In summary, the advantages of the present invention are:

[0017] 1. Compared to conventional serpentine or parallel flow fields, the present invention creates close contact between the spine region of the flow channel and the gas diffusion layer under a certain pressure. The diffusion layer is compressed at a certain ratio, causing microscopic changes in the porosity and pore structure of the gas diffusion layer in the compressed region, which increases the mass transfer resistance and makes drainage difficult. This improvement enhances the mass transfer and drainage capabilities of the flow channel while reducing the weight of the electrode plate. This increases the power density of the membrane electrode by 20-30%, overcomes the inconvenience of implementing a three-dimensional flow field, and features a simple molding process, low cost, and adaptability to membrane electrodes of various shapes.

[0018] 2. Since the flow of materials will generate a pressure drop in the flow field grooves, there will be a pressure difference at both ends of the flow field grooves connected by the capillary flow channels. By adding capillary flow channels in the ridge part of the flow field, and the capillary flow channels are at a certain angle to the material flow direction, the material can be promoted to diffuse and flow to the area under the ridge. At the same time, the water generated by the electrochemical reaction in the area under the ridge is quickly absorbed by the capillary adsorption of the microchannels and converges to the main channel, thereby enhancing the mass transfer and drainage capacity of the area under the ridge of the flow field.

[0019] 3. The angle between the capillary flow channel and the material flow direction ranges from 10 to 90 degrees. The greater the pressure difference between the two points of the flow field groove connected to the capillary flow channel, the greater the angle between the capillary flow channel and the material flow direction.

[0020] 4. In order to adapt to different shapes of membrane electrodes, the cross-sectional shape of the capillary flow channel can be set to semicircular, inverted triangle, rectangular or serrated as needed;

[0021] 5. In order to enhance the waterproofness of the capillary flow channel, the inner surface of the capillary flow channel is treated with a hydrophobic agent. The hydrophobic agent is PTFE or PVDF, which makes the capillary flow channel have good weather resistance, high temperature resistance, oxidation resistance and chemical corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of the flow field plate in Example 1 of the present invention;

[0023] Figure 2 Schematic diagram of the contact between the flow field ridge portion and the gas diffusion layer in Example 1 of the present invention;

[0024] Figure 3 for Figure 1 A partial enlarged schematic diagram of point A in the middle;

[0025] Figure 4 Schematic diagram of the structure of the flow field plate in the second embodiment of the present invention;

[0026] Figure 5 Schematic diagram of the structure of a serpentine flow field plate in the prior art;

[0027] Figure 6 This is a schematic diagram of the contact between the flow field ridge portion and the gas diffusion layer in the prior art;

[0028] Figure 7 It is a structural schematic diagram of a parallel flow field plate in the prior art.

[0029] Reference numerals:

[0030] 1. Flow field plate; 3. Flow field groove; 4. Flow field ridge; 5. Capillary flow channel; 6. Inlet; 7. Outlet; 8. Gas diffusion layer. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the overall concept of the present invention, the present invention is further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following words indicating orientation or positional relationships, such as "upper", "lower", "left", "right", "longitudinal", "lateral", "inner", "outer", "vertical", "horizontal", "top", and "bottom", are based solely on the orientation or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0032] Example 1

[0033] A high power density hydrogen fuel cell bipolar plate flow field, such as Figures 1 to 3 As shown, it includes at least one flow field plate 1, which includes a cathode and an anode surface, which are used for the transmission of oxidant and fuel respectively. An anode flow field channel is provided on the anode surface, and a cathode flow field channel is provided on the cathode surface. The anode flow field channel and the cathode flow field channel form a plurality of flow field grooves 3 in the anode surface and the cathode surface respectively, and the anode flow field channel and the cathode flow field channel form a plurality of flow field ridges 4 on the anode surface and the cathode surface respectively. The anode flow field channel and the cathode flow field channel are both connected by a plurality of flow field grooves 3, and a plurality of capillary flow channels 5 are provided between two adjacent flow field grooves 3. The capillary flow channels 5 are arranged between the flow field ridges 4 between the two adjacent flow field grooves 3, and are arranged at an angle to the material flow direction.

[0034] Because material flow generates a pressure drop within the flow field grooves 3, a pressure differential exists between two adjacent flow field grooves 3 connected by the capillary channel 5. The pressures of the two adjacent flow field grooves 3 connected by the capillary channel 5 are P1 and P2, respectively, with ΔP = P1 - P2 ≠ 0. This promotes the diffusion of material toward the area below the flow field ridge 4. At the same time, water generated by the electrochemical reaction in this area is rapidly absorbed by the capillary channel 5 and converges toward the main flow channel, enhancing the mass transfer and drainage capabilities of the area below the flow channel ridge.

[0035] It is understood that the angle between the capillary channel 5 and the material flow direction is Q, 10°<Q<90°. The greater the pressure difference between two adjacent flow field grooves 3 connected by the capillary channel 5, the greater the angle between the capillary channel 5 and the material flow direction.

[0036] It is understandable that the cross-sectional shape of the capillary flow channel 5 can be replaced by a variety of equivalent shapes, such as a semicircle, an inverted triangle, a rectangle or a sawtooth shape.

[0037] It is understood that the width of the capillary channel 5 is D, 0<D<0.5mm. Preferably, D=0.15mm. D can also be set to other reasonable values ​​such as 0.08mm, 0.12mm, 0.18mm, 0.24mm, 0.29mm, 0.33mm, 0.37mm, 0.46mm, etc.

[0038] It is understood that the depth of the capillary channel 5 is H, 0<H<0.3mm. Preferably, H=0.1mm. H can also be set to other reasonable values ​​such as 0.06mm, 0.09mm, 0.13mm, 0.19mm, 0.24mm, 0.28mm, etc.

[0039] To enhance the water resistance of the capillary channel 5, the inner surface of the capillary channel 5 is treated with a hydrophobic agent. The hydrophobic agent is PTFE or PVDF, which has good weather resistance, high temperature resistance, oxidation resistance, and chemical corrosion resistance.

[0040] In this embodiment, the flow field plate 1 is a serpentine flow field plate 1. An inlet 6 is provided at one end of the cathode flow field channel or the anode flow field channel, and an outlet 7 is provided at the other end of the cathode flow field channel or the anode flow field channel. Both the inlet 6 and the outlet 7 are connected to the cathode flow field channel or the anode flow field channel.

[0041] Example 2

[0042] Different from the first embodiment, Figure 4 As shown, the flow field plate 1 in this embodiment is a parallel flow field plate 1.

[0043] For other contents not described in this embodiment, please refer to the first embodiment.

[0044] In traditional serpentine or parallel flow fields, the ridge area of ​​the flow field flow channel and the gas diffusion layer 8 are in close contact under a certain pressure. The gas diffusion layer 8 is compressed at a certain ratio. The porosity and pore structure of the gas diffusion layer 8 in the compressed area are microscopically changed, resulting in increased material mass transfer resistance and difficulty in drainage.

[0045] The present invention improves the original flow field and enhances the mass transfer and drainage capabilities of the flow field while reducing the weight of the electrode plate, thereby increasing the power density of the membrane electrode by 20-30%, and overcoming the disadvantage of the inconvenience of implementing a three-dimensional flow field. The molding process is simple, the cost is low, and it is adaptable to membrane electrodes of different shapes.

[0046] In addition to the above preferred embodiments, the present invention has other implementation modes. Those skilled in the art can make various changes and modifications based on the present invention. As long as they do not depart from the spirit of the present invention, they should all fall within the scope defined by the claims attached to the present invention.

Claims

1. A high power density hydrogen fuel cell bipolar plate flow field, characterized by: It includes at least one flow field plate, which includes a cathode and an anode surface, which are used for the transmission of oxidant and fuel respectively. An anode flow field channel is provided on the anode surface, and a cathode flow field channel is provided on the cathode surface. The anode flow field channel and the cathode flow field channel form a plurality of flow field grooves in the anode surface and the cathode surface respectively, and the anode flow field channel and the cathode flow field channel form a plurality of flow field ridges on the anode surface and the cathode surface respectively. The anode flow field channel and the cathode flow field channel are both connected by a plurality of flow field grooves, and a plurality of capillary flow channels are provided between two adjacent flow field grooves. The capillary flow channel is provided in the flow field ridge between the two adjacent flow field grooves and is provided at an angle to the material flow direction; the angle between the capillary flow channel and the material flow direction is Q, 10°<Q<90°.

2. A high power density hydrogen fuel cell bipolar plate flow field according to claim 1, characterized in that: The pressures of two adjacent flow field grooves connected by the capillary flow channel are P1 and P2 respectively, and ΔP=P1-P2≠0.

3. The high power density hydrogen fuel cell bipolar plate flow field according to claim 2, characterized in that: The cross-sectional shape of the capillary flow channel is any one of a semicircle, an inverted triangle, a rectangle or a sawtooth.

4. A high power density hydrogen fuel cell bipolar plate flow field according to claim 3, characterized in that: The width of the capillary flow channel is D, 0<D<0.5mm.

5. The high power density hydrogen fuel cell bipolar plate flow field according to claim 4, characterized in that: The depth of the capillary flow channel is H, 0<H<0.3mm.

6. The high power density hydrogen fuel cell bipolar plate flow field according to claim 5, characterized in that: The inner surface of the capillary flow channel is treated with a hydrophobic agent.

7. The high power density hydrogen fuel cell bipolar plate flow field according to claim 6, characterized in that: The water repellent is PTFE or PVDF.

8. A high power density hydrogen fuel cell bipolar plate flow field according to any one of claims 1 to 7, characterized in that: The flow field plate is a serpentine flow field plate or a parallel flow field plate.

9. The high power density hydrogen fuel cell bipolar plate flow field according to claim 8, characterized in that: One end of the cathode flow field channel or the anode flow field channel is provided with an inlet, and the other end of the cathode flow field channel or the anode flow field channel is provided with an outlet, and the inlet and outlet are both connected to the cathode flow field channel or the anode flow field channel.

Images